The CO2-2e has two timers that are used to adjust the right amount of CO2 without the wasteful "overshoot" that other controllers have. One timer controls the length of time the CO2 is released and the other controls how often the CO2 is released. The result is a very efficient method of controlling CO2. It also features temperature and humidity controls which will disable CO2 injection if the temperature or humidity levels that you specify are exceeded, activating an exhaust outlet which can control ventilation equipment (air conditioner, fan, etc.) It also has a built in photo controller, which disables the CO2 function when the lights are off. The CO2-2e can be converted to PPM level accuracy with the addition of the PPM-1c CO2 sensor. The CO2-2e is rated for 15 amps @ 120 volts.